Abstract

Transcatheter aortic valve implantation (TAVI) is frequently associated with cardiac conduction defects (CCD) requiring permanent pacemaker implantation (PPI). Although new-onset left bundle branch block (LBBB) is often seen, the rate of progression to severe CCD is unclear. We aimed to find clinical and electrocardiographic (ECG) parameters associated with severe CCD requiring PPI in patients with a new-onset LBBB after TAVI and assess its effect on clinical outcome.

Methods and results

All consecutive patients undergoing TAVI who developed a new-onset LBBB were retrospectively analysed. We excluded patients with pre-existing bundle branch block or pacemaker. Patients were divided into two groups: with or without PPI after TAVI. We included 155 patients (50% female, 80 ± 7 years), of which 37 (24%) developed CCD requiring PPI, mainly due to a total atrioventricular block (
n
= 17; 46%). Cardiac conduction defects requiring PPI were associated with the following pre-existing parameters: atrial fibrillation (AF), the use of digoxin, CoreValve implantation, and left heart axis. Furthermore, it was associated with the following post-procedural parameters: left heart axis, lower mean heart rate, and prolonged PQ and QRS times. During follow-up, patients with PPI showed a lower mortality rate (11 vs. 29%,
P
= 0.03). In patients without PPI, mortality was lower in those with narrower QRS complex and transient LBBB.

Conclusion

The severity and persistence of a new-onset LBBB after TAVI is associated with mortality. Cardiac conduction defects requiring PPI are associated with prior AF, the use of digoxin, CoreValve implantation, and a left heart axis. In these patients, PPI portends a better prognosis than no PPI.

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What's new?

A more severe new-onset left bundle branch block (LBBB), characterized by its persistence (vs. transient LBBB) and a broader QRS complex, is more likely to progress to high-degree cardiac conduction defects (CCD) requiring permanent pacemaker implantation (PPI). A PPI in these patients is related with a lower mortality.

Atrial fibrillation, use of digoxine, CoreValve implantation, left heart axis, and longer PQ and QRS times after transcatheter aortic valve implantation (TAVI) are associated with severe CCD requiring PPI in patients with a new-onset LBBB post-TAVI.

Transcatheter aortic valve implantation (TAVI) has emerged as a therapeutic option for patients with severe symptomatic aortic stenosis who are at high surgical risk or inoperable.
1
,
2
Despite favourable clinical outcome, patients undergoing TAVI are at risk of new cardiac conduction defects (CCD) and subsequent need of a permanent pacemaker implantation (PPI).

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Issue Section:

Although human immunodeficiency virus (HIV) type 1 infection through heterosexual intercourse accounts for the majority of infections worldwide, the mechanism of viral transmission across the epithelium of the reproductive tract is poorly understood. The correlation between the presence of genital ulcerative diseases and HIV infection suggests that HIV may enter the body through lesions [
1
,
2
]. On the other hand, it has been shown that Rhesus macaques can be infected by simian immunodeficiency virus (SIV) placed on the apparently intact cervix, vagina [
3–5
], or penile urethra [
4
,
5
]. These studies suggest that lesions are not required for infection and that the virus is capable of crossing the epithelial barrier by an undefined mechanism

The epithelium separates the host from its environment and protects it from pathogens. Both the ectocervix and vagina of the female genital tract consist of stratified squamous epithelium; the endocervix is characterized by a simple columnar epithelium. All are considered potential sites for HIV-1 infection. A number of in vitro studies have shown that human genital epithelial cells can be infected through contact with infected monocytes [
6
,
7
] but are refractory to cell-free HIV-1 infection, presumably because of the lack of cell-surface CD4 cells. Previous studies have reported that ME-180, a cervix-derived, CD4-negative epithelial line, could be infected by contact with HIV-1–infected T cells [
7
,
8
]. Subsequently, studies have demonstrated that epithelial cells can be productively infected and that HIV-infected primary monocytes can also mediate infection [
9–11
]. However, epithelial cells, usually lacking surface CD4 cells, were generally difficult to infect by cell-free viruses in vitro, and the amount of virus detected after infection was very low [
12
]

It is therefore controversial whether genital epithelial cells can be productively infected by cell-free virus. In vivo studies have failed to provide consistent evidence of HIV-1 infection of genital mucosal epithelia. Some investigators have reported that no HIV-1 proteins or viral RNA were detected in the epithelial lining of the cervix or vagina [
5
,
13
], whereas others [
14
] have reported that Vibratome sections of living tissue and primary cell cultures from the human oviduct, uterus, cervix, and vagina could be infected by primary isolates of HIV-1

We report here that HIV-1 failed to infect a genital epithelial cell line derived from human cervical tissue. Instead, the cells sequestered large amounts of virus, and the virus remained infectious for a prolonged period. The sequestered virus could be efficiently transmitted to susceptible target cells through cell-cell contact. The observations implicate the possible roles of genital epithelial cells during sexual transmission of HIV in vivo and suggest that Ect1 cells can be a useful in in vitro models, for understanding the sexual transmission of HIV

“Your pseudoscience beliefs- common ancestry has to be assumed and cannot be tested- mean nothing to me. You don’t even know what makes a human a human nor a chimp a chimp so you don’t know if one can evolve into the other. All you have are slight changes plus eons of time- pseudoscience.”

While I will admit that common ancestry does not have to be assumed, the evidence that exists is so overwhelming that only a fool or someone suffering from some acute delusion would refuse to admit this. Moreover, what makes you think that I don’t know “what makes a human…… a chimp”? To leap to that conclusion is an exercise in abysmal logic.

As for Carl Zimmer’s qualifications to discuss biological research as significant as the latest on human chromosomal fusion, he’s demonstrated that ample times. You have yet to demonstrate once that you have any sound understanding of science, especially when you link to an article written by a Bible thumping Intelligent Design creationist. Methinks you need to read books written by Carl, Sean B. Carroll, Paul R. Gross and Barbara Forrest, among others, before commenting further here.

I didn’t ask for some ridiculous pseudoscientific drivel that attempts to explain the chromsome 2 fusion after it had already been discovered. I asked for an explanation for why evolutionary biologists were able to correctly predict the existence of this fusion before the technology even existed to demonstrate it. If it was the creationists who correctly understood human origins, we would be expecting them to be the ones making such predictions, wouldn’t we?